Police are also warning that the tainted meatballs contain levels of strychnine potentially lethal to humans.

Anyone who encounters the meatballs is advised to call 911 and only to handle them if absolutely necessary and with heavy gloves as the poison can be absorbed through the skin, police said.

The meatballs have apparently been deliberately placed in spots where dogs defecate in the area of Crestline, Burnett and Parkridge drives, according to police.

Campbell said that if a dog is believed to have eaten the meatballs the animal should be immediately taken to a veterinarian. San Francisco Veterinary Services, Pets Unlimited and All Pets offer 24-hour vet service, San Francisco Animal Care & Control spokeswoman Deb Campbell said.

She said that reports of the meatballs being found elsewhere in the city—including Noe Valley and Dolores Park—are unsubstantiated rumors.

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